1. Technical Field
The present invention relates to an inflatable vehicle occupant protection device, such as an air bag. In particular, the present invention relates to an air bag that can lie flat, when not inflated, to increase the ease of folding the air bag.
2. Description of the Prior Art
An air bag is typically made of a plurality of panels secured together, as by sewing. After the air bag is constructed, it needs to be folded into a compact shape for storage.
If an individual panel of an air bag is flat, that is, occupies a plane and has no significant curvature, inclination, elevation, or depression relative to that plane, the panel has a planar configuration, and can lie flat with no significant wrinkles. This feature makes it significantly easier to fold a flat panel as part of a completed air bag, in comparison to a panel that is not flat, that is, a panel that can not be made to lie in an essentially planar configuration with no wrinkles.
U.S. Pat. No. 6,086,092 discloses an air bag that includes a smaller air bag enclosed within a larger air bag. Inflation fluid is initially directed into the smaller air bag. When the smaller air bag fills, inflation fluid is directed from the smaller air bag into the larger air bag, to inflate the larger air bag. The smaller and larger air bags are both uniform in constructionxe2x80x94each bag is made from two circular panels sewn together around their peripheries. Each one of the panels in the air bag is flat.
The present invention is an air bag for, when inflated, helping to protect an occupant of a vehicle. The air bag comprises first and second panels that are substantially identical to each other. The first and second panels are secured to each other to define a first bag section having a first inflation fluid volume. The first panel has an inflation fluid inlet for enabling flow of inflation fluid into the first bag section. The second panel has an outlet portion defining an inflation fluid outlet for enabling flow of inflation fluid out of the first bag section.
The air bag further comprises third and fourth panels that are substantially identical to each other. The third and fourth panels are secured to each other to define a second bag section having a second inflation fluid volume. The third panel is secured to the second panel and is spaced apart from the first panel. The third panel has a mouth portion defining an inflation fluid opening for enabling flow of inflation fluid into the second bag section. The mouth portion of the third panel is aligned with the inflation fluid outlet of the second panel for enabling flow of inflation fluid from the first bag section into the second bag section.